1. Field of Invention
The present invention relates to a method for three-dimensional image reconstruction. More particularly, the present invention relates to a method for three-dimensional image reconstruction of basal ganglion.
2. Description of Related Art
In the late 1950""s and 1960""s, the most common use of stereotactic surgery was the placement of subcortical lesions to treat movement disorders, primarily the tremor of Parkinson""s disease. After the introduction of L-Dopa in 1968 for treating Parkinson""s disease, indication for stereotactic surgery decreased due to its complexity. However, long term treatment with large doses of L-Dopa can result in decreased therapeutic effects and cause serious complications, such as, paranoia and agitated melancholia.
In the past ten years, rapid advances in computer technologies have rekindled interest in stereotactic surgery that can replace medicinal intake and prevent the derived complications. Furthermore, more details of the structure and the functions for basal ganglion have been realized. Therefore, stereotactic surgery has become one of the most important therapies for basal ganglion.
However, it is difficult to find balancing ganglion nuclei in basal ganglion with a size of about 4 mm. In order to determine three-dimensional locations of balancing ganglion nuclei, stereotactic instruments together with electrical stimulation are used. Hence, balancing ganglion nuclei can be accurately determined and be electrocauterized for treatments.
Before the stereotactic surgery, the patient is sent to the neuro-internist for pre-operative evaluation and electrophysiological researches. Afterwards, the patient is transferring to the operating room. The patient is fitted with a stereotactic head ring assembly using local anesthesia. A computed tomography (CT) scan or a magnetic resonance imaging (MRI) scan is performed, and the data of the scan is then transformed and analyzed by stereotactic computers to form stereotactic atlases. Stereotactic atlases define target sites and stereotactic coordinates for the targets. The important functional segments of the brain are distinguished and the relative distances between target sites and those functional segments are shown in stereotactic atlases. As a result, neurosurgeons can simulate three-dimensional images and operational paths from different angles in the stereotactic computer for the accuracy and security of the operation.
In stereotactic researches focused on the brain, Dr. Kelly proposed that three-dimensional coordinates of the CT scans could be calculated in spatial relationship to anatomical landmarks. However, the spatial limits of the anatomical structures defined in relationship to these landmarks are accurate only in the anatomical brain specimens that produced the atlas, using the same anatomical scale.
In the past, it was assumed that the relative angles between the stereotactic coordinates and three-dimensional coordinates of the CT scan are fixed or that the deviation was insignificant. However, it does not necessarily reflect the geometry in an individual patient undergoing operation. Therefore, doctors have to readjust the stereotactic head ring assembly for repeated scanning, which can cause overdose radioactive exposure and a waste of medical resources. Since basal ganglion is small in volume, the accuracy of the operation depends heavily on the accuracy of the scale and angles for three-dimensional coordinates of the target.
The invention provides a method for three-dimensional image reconstruction for basal ganglion. A novel geometrical algorithm has been developed to interpret the coordinates of the scanned image based on the Atlas for Stereotaxy of the Human Brain (by Schaltenbrand and Wahren).
The invention provides a method for three-dimensional image reconstruction for basal ganglion. A novel geometrical algorithm has been developed to calculate the correction coordinates of the target based on the reference axial shift in the CT scan coordinate system. Furthermore, wavelet transform along with interpolation techniques are used to obtain continuous sectional images, and a three-dimensional image reconstruction is then performed to form the stereotactic atlas of basal ganglion.
The invention provides a method for three-dimensional image reconstruction for basal ganglion. The scanned images are processed with a region growing technique to extract automatically AC (anterior commissures) and PC (posterior commissures) for the reference scale and correction formulation of reference axis. The deviation angles between the reference axes of the CT scan coordinates and three standard axes are matrix transformed. Two-dimensional coordinates of each pixel in the boundary curve is transferred into three-dimensional CT coordinates. Wavelet transform and interpolation techniques are applied to reconstruct three-dimensional volume models along three axes. Furthermore, barycenters of three reconstructed three-dimensional volume models are overlapped with one another to obtain a maximum overlapping volume. The stereotactic atlas of basal ganglion is formed thereon.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.